Waste Management Inc. agreed to pay $457 million to settle a class-action lawsuit alleging securities-law violations and said it expects to receive $20 million in a related settlement with its auditor.

The Houston trash hauler also reported third-quarter net income of $30 million, or five cents a share, compared with a year-earlier loss of $191 million, or 31 cents a share. The latest results reflect the proposed settlements. Revenue...